It is the objective of this study to determine separately the effects of both inhalation of smoke produced from marijuana, and parenteral administration of delta-9-THC on pulmonary bacterial susceptibility in the rat. Using techniques developed in our laboratory, pulmonary bacterial susceptibility will be assessed by determining: 1) the capacity of the lung to clear itself of bacterial insults; 2) changes in the number of alveolar macrophages; 3) changes in phagocytic capabilities of alveolar macrophages, and circulating neutrophils; 4) changes in intracellular killing capabilities of alveolar macrophages and circulating neutrophils; 5) effects on the mortality rate; and 6) pathologic changes. The final results of the short-term marijuana study using Pseudomonas aeruginosa will be completed shortly, and will be compared to the evaluation of mortality and alveolar macrophage functions following challenge by Staphylococcus aureus, currently underway. This data has produced a dose-response relationship for single dose administration of parenteral delta-9-THC injections and marijuana smoke inhalation. Using this information as control baseline data, long-term studies have been started. During the next year of this program, evaluation of mortality, alveolar macrophage functions, lung bacterial clearance, bacteriology, and pathology will be performed on rats exposed to marijuana smoke in long-term studies, up to six hours daily for 3 weeks, as well as continuation of the short-term study to include exposures up to six hours.